Mutants of
            <i>Escherichia coli</i>
            B/r Defective in Deoxyribonucleic Acid Initiation:
            <i>dnaI</i>
            , a New Gene for Replication

Beyersmann, Detmar; Messer, Walter; Schlicht, M.

doi:10.1128/jb.118.3.783-789.1974

Cited by 84 publications

(21 citation statements)

References 19 publications

(22 reference statements)

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“…Several temperature-sensitive mutations (1,6,7,18,39) and a few amber mutations (21,34) map in the dnaA gene of Escherichia coli. The phenotype of the dnaA mutants shows that the gene product is essential for initiation of chromosome replication.…”

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confidence: 99%

Effect of dnaA and rpoB mutations on attenuation in the trp operon of Escherichia coli

Atlung¹,

Hansen²

1983

J Bacteriol

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The rate of synthesis of tryptophan synthetase was found to be increased by heat inactivation of the dnaA protein in three dnaA mutants temperature sensitive for initiation of DNA replication. The effect of the dnaA mutations was dependent upon the presence of an intact attenuator in the tryptophan operon. The activity of the mutated dnaA protein at the tryptophan attenuator and its activity as initiator for chromosome replication decreased gradually with increasing temperature. Two rpoB mutations that suppress the temperature defect of the dnaA46 mutation in initiation of replication were tested for effects on attenuation in the tryptophan operon. One of the rpoB mutations caused increased transcription termination at the attenuator independent of the dnaA allele, whereas the other mutation had no effect. Expression of the histidine and threonine operons, which are also regulated by attenuation, was unaffected by the dnaA mutations. the aromatic amino acids per ml, 100 ,ug of serine, leucine, and arginine per ml, and 50 pg of the other amino acids, except cysteine, per ml. In some experiments tyrosine or histidine was omitted depending on the enzyme assays to be carried out in addition to the measurements of tryptophan synthetase (TSase).Preparation of P1 lysates and Pl transductions were carried out as described by Miller (27). Deo+ transductants were selected on AB minimal plates supplemented with 0.2% thymidine as the carbon source, and Tna+ transductants were selected on 985 on August 2, 2020 by guest

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confidence: 99%

Effect of dnaA and rpoB mutations on attenuation in the trp operon of Escherichia coli

Atlung¹,

Hansen²

1983

J Bacteriol

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“…Bacteria and growth conditions. E. coli B/r WM301 dnaI (arg, dra or drm; gal, his, lac, leu, met, pro, Strr, thy, trp, hspKl2) was isolated by Beyersmann et al (1) and obtained from the E. coli Genetic Stock Center. E. coli B/r dnaC2 has been described elsewhere (C. E. Helmstetter, submitted for publication).…”

Section: Methodsmentioning

confidence: 99%

Coordination between chromosome replication and cell division in Escherichia coli

Tang¹,

Helmstetter²

1980

J Bacteriol

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Cell division properties of Escherichia coli B/r containing either a dnaC or a dnaI mutation were examined. Incubation at nonpermissive temperature resulted in the eventual production of celLs of approximately normal size, or slightly smaller, which lacked chromosomal DNA. The cell division patterns in cultures which were grown at permissive temperature and then shifted to nonpermissive temperature were consistent with: first, division and equipartition ofchromosomes by cells which were in the C and D periods at the time of the shift; second, an apparent delay in cell division; and third, commencement of the formation of chromosomeless cells. In glucose-grown cultures of the dnaI mutant, production of chromosomeless cells continued for at least 120 min, whereas in the dnaC mutant chromosomeless cells were forned during a single interval between 110 and 130 min after the temperature shift. The results are discussed in light of the hypothesis that replication of a specific chromosomal region is not an obligatory requirement for the initiation and completion of the processes leading to division in a cell which contains at least one functioning chromosome. 1148 on August 1, 2020 by guest

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“…In this study we have chosen to reinvestigate the dnaA204 mutant, which is a member of the irreversible category (Beyersmann et al, 1974;Tippe-Schindler et al, 1979) by using flow-cytometric and marker-frequency analytical techniques.…”

Section: Introductionmentioning

confidence: 99%

Reversibility of DnaA protein activity in the‘irreversible’dnaA204 mutant of Escherichia coli

Hansen

Atlung

1995

Molecular Microbiology

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The dnaA204 mutant, one of the so-called irreversible dnaA mutants which cannot reinitiate chromosome replication upon a shift from non-permissive to permissive growth temperature in the absence of protein synthesis, was reinvestigated using flow cytometry and marker frequency analysis. In a temperature down-shift experiment and in the presence of protein synthesis the dnaA204 mutant reinitiates chromosome replication very fast. Using a lac promoter-controlled wild type or a dnaA204 mutant gene carried on a plasmid, we have observed instantaneous initiation of replication when synthesis of DnaA protein is induced in the dnaA204 mutant at 42 degrees C. The data indicate that the dnaA204 mutant after a shift to 42 degrees C still contains functional DnaA protein, but that the activity level is below the initiation threshold. Thus, after synthesis of very small amounts of additional DnaA protein, initiation occurs very fast both after a shift to 30 degrees C, and after induction of DnaA protein synthesis at 42 degrees C. A model describing the processing of DnaA protein in mutants and in the wild type is presented.

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Mutants of Escherichia coli B/r Defective in Deoxyribonucleic Acid Initiation: dnaI , a New Gene for Replication

Cited by 84 publications

References 19 publications

Effect of dnaA and rpoB mutations on attenuation in the trp operon of Escherichia coli

Effect of dnaA and rpoB mutations on attenuation in the trp operon of Escherichia coli

Coordination between chromosome replication and cell division in Escherichia coli

Reversibility of DnaA protein activity in the‘irreversible’dnaA204 mutant of Escherichia coli

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